1. Field of the Invention
The present invention is related to certain photodynamic medicaments and methods for treatment of human or animal tissue using photodynamic therapy (PDT). The inventors of the present invention have found that such medicaments are useful for the treatment of a variety of conditions affecting the skin and related organs, the mouth and digestive tract and related organs, the urinary and reproductive tracts and related organs, the respiratory tract and related organs, the circulatory system and related organs, the head and neck, the endocrine and lymphoreticular systems and related organs, various other tissues, such as connective tissues and various tissue surfaces exposed during surgery, as well as various tissues exhibiting microbial, viral, fungal or parasitic infection. These medicaments are available in various formulations that may include liquid, semisolid, solid or aerosol delivery vehicles, and are suitable for intracorporeal administration via various conventional modes and routes, including intravenous injection (i.v.), intraperitoneal injection (i.p.), intramuscular injection (i.m.), intracranial injection (i.c.), intratumoral injection (i.t.), intraepithelial injection (i.e.), transcutaneous delivery (t.c.), and per oesophageal (p.o.) administration. These photoactive ingredients contain intracorporeal medicaments, the photoactivation of which produces a desirable therapeutic response, such as destruction of microbial infection, reduction or elimination of tissue irritation, reduction or elimination of hyperproliferative tissue, reduction or elimination of cancerous or precancerous tissue, reduction or elimination of surface or subsurface lipocytes or lipid deposits, and many other similar indications.
2. Description of the Related Art
PDT was originally developed to treat cancer and other diseases with the promise of limiting the invasiveness of the therapeutic intervention and lessening potential collateral damage to normal, non-diseased tissue. In its simplest form, PDT is the combination of a photosensitive agent with special forms of illumination to produce a therapeutic response in certain tissues, such as a tumor. The agent attains an excited, active state when it absorbs one or more photons, and then is or becomes efficacious. Key elements of a successful PDT regimen include either selective application or selective uptake of a photosensitive agent into the diseased tissue and site-specific application of the activating light. PDT agents are typically applied systemically (for example, via intravenous injection or oral administration) or via localized topical application directly to diseased tissues (for example, via topical creams, ointments, or sprays). Subsequent to administration of the agent (typically 30 minutes to 72 hours later), activating light is applied to the disease site, locally activating the agent, and destroying the diseased tissue. Light is typically applied by direct illumination of the site, or by delivery of light energy to internal locations using a fiberoptic catheter or similar approach.
Most current PDT regimens are based on systemic application of porphyrin-based agents or topical or systemic application of psoralen-based agents. Examples of porphyrin-based agents include porfimer sodium (PHOTOFRIN®), hematoporphyrin-derivative (HPD), benzoporphyrin derivative (BPD), Lutex, BOPP and SnET2. PHOTOFRIN® is one of the few agents currently licensed by the U.S. FDA. Porphyrin-based agents generally are derived from complex mixtures of natural or synthetically prepared materials and may contain components that are lipophilic. As a possible result of this lipophilicity, porphyrin-based agents have shown a slight tendency to accumulate preferentially in some tumors and other diseased tissues. However, the targeting of such agents to diseased tissue is still unacceptably low when compared to uptake in normal tissue, (i.e., at most 2-10× greater uptake in diseased tissue relative to normal tissue). The psoralens, such as 8-MOP, 5-MOP, trioxsalen, and AMT, are nucleic acid intercalators that function by disrupting cell regulation or impairing cellular physiology upon photoactivation. This mechanism of action appears to be relatively indiscriminate in terms of tissue type, and as a result these agents also exhibit minimal specificity for diseased tissue. Thus, current PDT agents have not exhibited high specificity and may exhibit additional disadvantages, including persistent systemic or localized photosensitivity, systemic or localized toxicity, and high treatment cost (due to high agent cost or excessive dosage requirements).
Consequently, PDT has not become widespread, given these background problems of target specificity and cost of treatment.
Therefore, it is an object of the present invention to provide new medicaments, new medical uses for such medicaments based on improved specificity of such medicaments for the desired target tissue to be treated, and methods for treatment using such medicaments, thereby resulting in improved treatment outcomes, increased efficacy and safety and reduced cost of treatment.